are compressors made for a set temperature?

[steve thailand]

hi again

sorry but i have yet another stupid question.

i have an industrial chiller unit i use for cooling my beer tanks. its 14KW and the lowest water outlet temperature i can set is 5 degrees C.

i bought this because 5 degrees is ok for brewing but it turns out its not cold enough for bottling, i need to get the beer down to about 1-2 degrees.

i don't want to buy another chiller so i was thinking i could mess with the temperature probe on the cold water outlet. i can change the resistance so it reads 5 degrees when it is colder, say 1 or 2 degrees.

this will cause the compressor to run longer but that should not be a problem because 14KW is over capacity anyhow. the compressor typically runs for about 1 minute and then off for about 2-3 minutes so there is plenty of spare capacity.

what i wonder is, will a compressor that is designed to cool water to 5 degrees be happy if i force it to cool water to say 1 degrees?

what about if i force it to -5 degrees? (i know i'll need to put glycol in the water tank)?

will i damage the compressor or something else?

thanks, steve

[NoNickName]

You can't set it at a lower temperature just because the manufacturer set a limit on the lowest settable setpoint.
It's reasonable because the evaporating temperature is presumably 5-7K below the leaving water temperature.
If you set it at a lower temperature, the evaporating temperature would probably cause progressive freezing of water and your evaporator will burst.
Unless you plan to add antifreeze to water and ask to the chiller manufacturer for the password to change the lowest setpoint limit in the programming menu, I would suggest to stick with it.
Changing the chiller will not help, because you would end up with the same scenario.

[steve thailand]

thanks, i will add 20% glycol to the chiller water so i think i should be good down to zero or maybe a little below

the manufacturer did tell me how to lower the setpoint and said i can go down to 1 or 2 degrees but do not go below zero

i can set it to below zero now but do you think it could damaging anything, assuming no problem with freezing the water tank with glycol in it.

thanks

[NoNickName]

You need to know the corresponding evaporating temperature and set the brine solution for that temperature.
30% is enough for -17°C, 20% should be around -10°C.
The cooling capacity will reduce correspondingly to the setpoint.

[Peter_1]

Most chillers are limited to an outlet of 2 to 4°C because you can't use them with pure water for lower temperatures.
But when adding glycol, there's no problem to go lower. Your only problem you have to solve is freezing up the heat exchanger. Which can be solved with glycol. Use glycol that is allowed to use in food systems.
Bear in mind that as NNN said you capacity will reduce first to the lowered suction pressure and 2nd also due to adding glycol to the system.
What brand of chiller is it?

[steve thailand]

Most chillers are limited to an outlet of 2 to 4°C because you can't use them with pure water for lower temperatures.
But when adding glycol, there's no problem to go lower. Your only problem you have to solve is freezing up the heat exchanger. Which can be solved with glycol. Use glycol that is allowed to use in food systems.
Bear in mind that as NNN said you capacity will reduce first to the lowered suction pressure and 2nd also due to adding glycol to the system.
What brand of chiller is it?

thanks, that's good news that i should be able to set it close to zero without a problem then with 20% gylcol in the water tank.

i can buy Ethyl Glycol or Propylene Glycol,is there are reason to choose one over the other?

(oh, i just found a thread about this, it looks like the propylene one is environmentally friendly and better for food use)

its a Chinese make, Dalen

thanks

[NoNickName]

Propylene is lesser toxic.

[MilosBog]

Water heat capacity will change by adding a glycol so if you can,check do you have a reserves on the capacity of the heat exchanger(if you have one). You need a bigger flow for yours 14 kW

[Sserrviceman]

Some info about Brewery Glycol System. Look in Google - EVERYTHING YOU WANTED TO KNOW ABOUT GLYCOL A Brewery Glycol System Guide.